The invention relates to flat panel displays, and more particularly to control knob apparatus for equipment utilizing such flat panel displays.
Flat panel displays are widely used in applications where the depth dimension of a cathode ray tube is determined to be excessive. Space considerations are also often critical with respect to the available surface area to be used by the apparatus having a flat panel display. Control knobs for adjusting equipment utilizing flat panel technologies are located at the periphery of the flat panel display given the operating principles of flat panel technology.
As a means of illustration, but not limitation, high level operational theory of Liquid Crystal Displays (LCDs), one type of flat panel technology is provided. Such displays are typically constructed of rectangular surface dimensions. Customizing specific flat panel display surface geometrical designs for low to moderate volume production runs can be prohibitively expensive.
The principle of operation of LCD's is well known in the art but for purposes of understanding the background of the present invention, it can be stated that LCD's operate by reducing the transmissibility of light through a thin layer of a liquid crystalline material when an electric field is applied. Since the effect is localized, shapes and characters can be drawn on an LCD by carefully controlling the application of the electric field. Unlike cathode ray tubes which LCD's are replacing, LCD's are not self-illuminating. This does not normally affect daylight use, but under night or other low light level conditions some sort of backlighting is required in order for LCD's to be viewed. Very high brightness ambients also require additional backlight brightness to maintain readability.
One area that has found widespread acceptance of instrumentaion having flat panel displays is the field of avionic equipment. Although not constrained to avionic LCD applications the present invention will be described in terms of such usage. It is understood that the teachings of the present invention are not limited to avionic LCD applications but may be utilized by any flat panel display.
To place cable wires or other means of conduit connecting a control knob located on the screen periphery to control means within the subject equipment requires limiting LCD dimensions in order to accomodate the hard wiring to the knob. Side mounting of the knob is generally not available because of the location of immediately adjacent equipment having display in the same geometrical plane as the flat panel display of the subject equipment. Similarly, location of control knobs at some location away from the subject equipment creates confusion, safety concerns and logistical problems connecting the control knobs to the appropriate control circuitry or devices.
Thus, a need exists for maximizing the surface area of the flat panel display while maintaining peripherially located control knobs for the associated equipment.